Just Replaced 12V battery- strange smell

welcome!
where is the smell emanating from?

 

could it have been leftover from the old battery? maybe hydrogen sulfide, or whatever batteries produce.

 

When was the last time that you inspected the cabin air filter? Maybe you have a dead mouse somewhere...

 

It could also be the traction battery vent tubes (the ones attached to the cells right inside the battery pack). Apparently they sometimes soften and degrade. I've never experienced it myself, only a minority of owners have the problem, but those that do say that it smells really awful.

 

Let's hope.
And that it is not the smell of electrical parts burning........caused by crossing the leads the last time it was jumped.

 

The natural smells from a lead-acid battery can be like eggs, as you mentioned, or a bit like a salad (it is acidic, after all, if sulfuric rather than acetic). A more 'chemical' smell reminds me more of the smell of wire insulation when wiring overheats. A pretty familiar melty-plastic smell.

You could get a geeky friend to melt some wire insulation for you, and see if the smell is like that. It might not be exactly the same, unless you can get a hunk of the same kind of wire Toyota uses to try with.

From the story that you had the smell before changing the battery, didn't notice it while doing the swap (no power), then noticed it again 5 minutes after power restored, I could be talked into an electrical fault somewhere in your car, which could also be what was draining the old battery again and again in the first place. That would be likely to get worse over time, which you don't want. You might see if you have a friend with a mighty nose who can help you better narrow it down to a place in the car.

-Chap

 

Are you the original owner? if not, you can never be sure what was done on the car before you owned it.
I agree with Chapman, electrical, something getting hot. I like Patrick’s suggestion also.

 

If you keep noticing the smell, finding the battery drained, or both, there are "battery saver" switches like this one that you can use at one of the battery posts.

It is only a stopgap until you can locate the fault and fix it, but allows you to twist a knob and completely disconnect the battery, preventing it from draining, and not sending more power to the faulted area, especially when the car is unattended. It will cut power completely off, meaning you lose your radio stations, etc., and will need the mechanical key to open the car. You might also consider not parking close to the house, until the problem is fixed.

It doesn't matter which battery post you put one of these on; they are usually shown on the + post, but they're also usually uninsulated, which would make me prefer to put it on the − post. Works the same either way.

-Chap